> ... your elevation angle is pretty high if you want to target the Earth-Moon L1 point or the Earth or LEO...
You don't point at where you want to go. You point retrograde (relative to the moon's orbit) so that, after escaping the moon, the payload is just past the apogee of a transfer orbit with the desired perigee.
Further, the moon isn't a flat disk, with the Earth "up"; getting the required angle is just a matter of choosing the right place on the surface of the moon (a sphere has multiple tangents pointing in any direction you want).
So no, you wouldn't need "a slanted hole a few km deep".
You may be right but I'd want to see the trajectories numerically integrated and plotted. What I know is that trajectories that hit the L1 point with low velocity will confound your intuition that comes from conics. Here is a recent analysis that considers a range of trajectories launched from a certain point
https://www.sjsu.edu/ae/docs/project-thesis/Ethan.Miller-Su2...
which a student project that has a lot of problems and doesn't consider the possibility of relocating the driver but they are considering moderately high angles of around 30 degrees. Their mass driver is about 500m long in the range that if you want to drill a hole that deep you can drill a hole that deep.
Practically there are other concerns about a moon base, particularly these days people are interested in polar locations. You could possibly run 1000 km of maglev to get to the base of the thing but if you are talking that big you might consider a lunar beanstalk which at least doesn't require a catcher at L1.
A lunar beanstalk? How is that supposed to work? (Answer: it won't; Lunar-stationary orbits do not exist, since they would have a radius on the order of the Earth-moon distance, and the Earth is much more massive than the moon).
https://explainingscience.org/2025/08/19/lunar-stationary-or...